Exposed crystal facets of WO3 nanosheets by phase control on NO2-sensing performance

• Published in: Journal of materials science. Materials in electronics Vol. 31; no. 1; pp. 610 - 620
• Main Authors: Song, Wanqing, Zhang, Rui, Bai, Xue, Jia, Qianqian, Ji, Huiming
• Format: Journal Article
• Language: English
• Published: New York Springer US 2020; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Crystals; Detection; Exposure; Hydrothermal crystal growth; Materials Science; Nanosheets; Nitrogen dioxide; Optical and Electronic Materials; Phase control; Selectivity; Sensors; Tungsten oxides
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-019-02565-6

WO 3 is a traditional type of NO 2 -sensing material. There are still some problems in relevant studies, such as high detection limit, high working temperature, and complex process. In this paper, simple hydrothermal method was used to prepare monoclinic WO 3 (M-WO 3 ), triclinic WO 3 (T-WO 3 ), and hexagonal WO 3 (H-WO 3 ) nanosheets. The NO 2 -sensing performance of T-WO 3 sensors is the best among these three phases. The response of T-WO 3 toward 300 ppb NO 2 at its optimum working temperature (100 °C) is 18.8. The selectivity and stability toward NO 2 are also great. The differences of NO 2 -sensing performances existed between different phases of WO 3 , owing to different exposed crystal facets. The T-WO 3 sensors have excellent ppb-level NO 2 -sensing performance at low working temperature, owing to more O 1c active sites on the main exposed crystal (200) facet, and NO 2 molecules are easily adsorbed at O 1c active sites, which is the root cause of the better sensing performance of T-WO 3 toward NO 2 . These results show that T-WO 3 nanosheets sensor can be seen as a competitive candidate for low concentration NO 2 detection, and this study can be regarded as a basic research on improving gas-sensing performance of sensitive materials by controlling the exposed crystal facets.